Blackboard



J. GROTHAUS.

BLACKBOARD. APPLICATION FlLED'lUNE 23, 1920.

1,379,96 1 Patentbd Mar. 8, 1921.

\ avwwtoz UNITED STATES PATENT OFFICE.

JULIA GRO'IHAUS, OF FORT SAM HOUSTON, TEXAS.

BLACKBOARD.

To all whom it may concern Be it known that I, JULIA GROTHAUS, a citizen of the United States, residing at Fort Sam Houston, in the county of Bexar and State of Texas, have invented certain new and useful Improvements in Blackboards, of which the following is a specification.

The invention relates to display boards and more particularly to display boards known as black-boards.

The object of the invention is to provide a display or black-board for use in schools or brokerage ofiices wherein the whole or only a part of the writing may be displayed at one time although the board may be completely covered therewith.

A further object is to provide a board of the above mentioned character wherein a portion of the writing thereon may be hidden from View by reason of the boards being raised, lowered, or rotated and the board so secured as to prevent unauthorized persons from arranging the same so that the hidden portion may come into view.

A further object is to provide means to increase the usual limited black-board space in school rooms and at the same time to bring the top of the board, which is usually not used, within reach of the writer from the floor level, after which it may be raised to a higher point.

With these and other objects in view, the invention resides in the several novel parts and devices combined and arranged as hereinafter described and claimed.

In the accompanying drawings, in which like reference characters indicate corresponding parts and in which I have illustrated one embodiment of my invention:

Figure 1 is a front view of the preferred form of my device.

Fig. 2 is a sectional view of Fig. 1.

Fig. 3 is a longitudinal sectional View of the preferred form of locking device for the boards.

Fig. 4 is a plan view of Fig. 3 with certain parts removed to show the essential features of the device more clearly.

Figs. 5 and 6 are sectional views of Fig. 3 on the lines a: w and 2 a respectively.

In the application of my improvement I have designed an endless chain of slats A of suitable proportions and suitably joined, to be mounted over rollers B, the rollers in turn being carried on shafts C, the said Specification 01' Letters Patent.

Patented Mar. 8, 1921. 1920. Serial No. 391,167.

shafts being supported by bearers D, guides E carried by the shafts C being provided in order to prevent the chain of slats from sagging between rollers. At suitable intervals and at a desired distance from the ends of the slats A I have provided holes F for the double purpose of providing a catch for inserting the finger for rotating or raising the board and for the purpose of receiving the latch of the locking device which is hereinafter described.

The locking device consists of a suitable frame L, a fiat spring steel piece M on which is mounted at its free end a lug N adapted under certain conditions to enter the holes F for the purpose of securing the board against rotation, raising or lowering. In order to control the lug N and prevent its entering the holes F, or if it is desired to lock the board to prevent its being forced out of locked engagement by unauthorized persons after the locking device has been actuated to prevent rotation or shifting of the board, I have provided a latch O, the same being provided with a pivot P P, the upper pivot being extended at Q and formed into a stem of square cross section to receive a key, a small boss R being mounted over the stem for a finish.

For the purpose of better showing the device I have indicated the latch O in a sort of neutral position with respect to the flat spring M of the locking device; obviously in this position the lug N would be in engagement with one ofthe holes F but would not be locked until the latch O was rotated clockwise until the face S was under the spring in order to prevent the lug N being pushed out of locked relation with a hole F. On the other hand, if the latch be rotated anti-clockwise from its present position until the face T is disposed over the spring M and substantially at right angles thereto the spring will be depressed until the lug N is withdrawn from the hole F, allowing the sash board or the endless chain board free movement. The slanting surfaces S and T of the latch are for the obvious purpose of gradually wedging the spring M to either the locked or unlocked position, depending upon the direction the latch is rotated. The two flat surfaces S and T are the extreme positions of engagement or release of the spring. I have not so indicated in the drawings, but I may in some instances install a crank arrangement for rotating the endless chain board as a refinement. The seams U on the endless chain type of board will be faintly visible and will form a horizontal guide to assist the writer in making neat, uniform writing.

In my device it is to be understood that I do not limit myself to any particular m a-- terial, size, proportion, or details except in so far as such limitations are specified.

I claim: x

1. In combination, a stationary frame, a

plurality of thin strips joined in a manner to form an endless chain, two rollers mounted in said frame for carrying said endless chain, a plurality of perforations near the ends of said strips, and a locking device secured to said stationary frame adapted to engage under certain conditions in one of the said perforations. V

2. In combination, a stationary frame, a plurality of thin strips joined in a manner to form an endless chain, two rollers mounted in said frame for carrying said endless chain, a plurality of perforations near the ends of the above mentioned strips, a metal strip pivotally mounted in said stationary frame, a lug carried by said metal strip and adapted to engage in any one of said perforations when brought into register with said lug, .and means for mechanically removing or preventing the removal of the above mention ed lug.

' 3. In combination, a stationary frame, a plurality ofthin strips joined in a manner to form an endless chain, two rollers mounted in said frame for carrying saidendlesS. chain, a plurality of perforations near the ends of the above mentioned strips, a metal strip pivotally mounted insaid stationary frame, a lug carried by said metal strip and adapted to engage in any one of said perfo JULIA 'GROTHAUS. 

